Abstract: A controller and corresponding method have been developed for controlling recharging of a water conditioning apparatus. The apparatus includes an input component for receiving measurements of water usage by the apparatus, a storing component configured to store, for each time slot of a cyclically repeating series of time slots, values dependent upon an average of the measured amounts of usage in that time slot and in at least one other corresponding time slot in a previous cycle, and a determining component configured to determine, at least in part, a time for recharging the apparatus in dependence upon the stored value.